1. Technical Field
The present invention relates to a projector.
2. Related Art
A projector which uses a discharge lamp such as a high pressure mercury lamp or a metal halide lamp has been put into practical use. As such a projector, for example, in JP-A-2003-102030, a projector is disclosed which includes means for changing the intensity of a light source through color separation means or the like in synchronization with an image signal. However, JP-A-2009-237302 discloses that if the intensity of the light source is simply changed, there is a problem that electrode wear of a discharge lamp becomes noticeable.
Further, in recent years, a projector which uses a discharge lamp such as a high pressure mercury lamp or a metal halide lamp and outputs a stereoscopic image has been put into practical use.
As an example of a method of outputting the stereoscopic image, there is a method of switching and alternately outputting a right-eye image and a left-eye image (for example, an active shutter glasses type such as “XPAND beyond cinema (trademark of X6D Limited)”). In this method, the right-eye image is viewed with the right eye and the left-eye image is viewed with the left eye using active shutter glasses or the like which are synchronized with an image signal, and thus, the image is viewed stereoscopically using the parallax between the left eye and the right eye.
In a case where a stereoscopic image is projected using the method of alternately outputting the right-eye image and the left-eye image, compared with a case where a planar image (two-dimensional image) is projected in the related art, the amount of light which enters the right eye and the left eye becomes half or less. Further, if crosstalk occurs in which the right-eye image enters the left eye and the left-eye image enters the right eye, the image is not perceived stereoscopically, and thus, a period when both of the active shutters are closed is necessary. Thus, in a case where the stereoscopic image is projected using the method of alternately outputting the right-eye image and the left-eye image, compared with a case where the planar image is projected in the related art, there is a problem that the image appears dark. In order to cause the image to appear bright, a method of simply increasing drive power may be considered. However, in this method, for example, there is a problem that the power consumption of the projector is increased or deterioration of peripheral parts is facilitated as the power consumption is increased.
Further, if a control is performed so that the luminance of the discharge lamp is decreased in a period when both the active shutters are closed and is increased in a period when any one of the active shutters is opened in order to cause the image to appear bright, the temperature of the electrode of the discharge lamp is decreased in the period when the luminance of the discharge lamp is decreased, and the meltability of the tip end of the electrode becomes insufficient, so that the electrode may be deformed. If the electrode is deformed, the occurrence of flickering or the like may be caused. If flickering occurs, the brightness of an image projected during usage of the projector is changed.
In particular, in a case where the drive current of the discharge lamp is decreased as the state of deterioration of the discharge lamp proceeds, the brightness of the discharge lamp is decreased and the meltability of the tip end of the electrode becomes insufficient, and thus, the electrode is easily deformed. Thus, in order to project the stereoscopic image to appear bright while suppressing deformation of the electrode, a particular consideration is necessary.